The invention relates generally to apparatus and methods for remodulating video signals. More particularly, the invention relates to apparatus and methods for encoding digital video components such as luminance (Y) and color difference (R-Y, B-Y), the apparatus and methods beings useful in conjunction with picture-in-picture (PIP) video technology.
PIP systems which utilize digital video component encoders are well known in the art. Details of one such system are given in Masuda, Michio et al., "Picture in Picture System With a Digital Memory for VCRS", IEEE Transactions on Consumer Electronics, Vol, CE-33 No. 3; (Aug. 1987, pp. 230-238). As disclosed therein, the digital video components Y, R-Y, and B-Y are multiplexed, A/D converted, and then stored in memory for use at the appropriate time for a PIP display. When read from the memory, the R-Y and B-Y components are encoded by a digital quadrature modulation circuit and are then converted into analog form by a D/A converter. The Y component, which is not subjected to digital quadrature modulation, is likewise transformed into an analog signal by a separate D/A converter. The analog signals are then added by an analog adder prior to being sent to the television for output as PIP information on a video display.
While the PIP system provided by Masuda et al. is advantageous in many respects, it should be appreciated that it is desirable in a commercial environment to efficiently utilize circuitry so as to reduce costs. Also, it will be appreciated that the PIP system of Masuda et al. does not provide for the remodulation of composite video data, but rather only remodulates the luminance and color difference components.